Train-control system for railroads



June 11, 1929. c. s. BUSHNELL 1,717.332

TRAIN CONTROL SYSTEM FOR RAILROADS Original Filed Jan. 26- 2 2 Sheets-Sheet l FIG.1

@5 cfiwveuboz @MMQZZL June 11, 1929.

C. S. BUSHNELL TRAIN CONTROL SYSTEM FOR RAILROADS Original Filed Jan. 26. 1922 neg 2 Sheets-Sheet 2 I FIGS. g

1 Q 141 I45 n40 144 'Y' "H I44 ii ii 143' Patented June 11, 1929.

UNITED STATES 1,717,332 PATENT OFFICE.

CHARLES S. BUSHNELL, OF ROCHESTER, NEW YORK, ASSIGNOR T GENERAL RAIL- WAY SIGNAL COMPANY, OF ROCHESTER, N EW YORK.

TRAIN-C'ONTROL SYSTEM FOR RAILROADS.

Original application filed January 26, 1922, Serial No. -531,903. Divided and this application filed.

November 22, 1926.

This invention relates in general to automatic train control systems for railroads and has moreparticular reference to a semi-automatic or permissive type of system.

The present application is a division of my co-pending application, Ser. No. 531,903 filed J an. 26, 1922, for train control systems for railroads.

In train control systems, it is necessary to transmit or communicate controlling influences or impulses from the trackway to moving vehicles, in order that the train control apparatus on each vehicle may be governed in accordance with the presence or absence of other vehicles, positions of switches, and other conditions affecting the safe progress of the vehicle. On account of weather conditions, problems of clearance, and like difficulties encountered in practice, it is desirable to communicate such controlling influences inductively, that is, through an intervening air gap, rather than by a me chanical cooperation or physical contact between devices on the vehicle and devices on the track. -With a view to satisfying the principle of failure on the side of safety, so important in railway signaling and train control systems, it is considered preferable to employ an arrangement of car apparatus and trackway devices which will actto produce a stopping influence in case of any failure of circuits or the like; and it is proposed to utilize the magnetic properties of an inert body of iron on the trackway for producing the stopping influence. Since it is desirable to avoid the use of batteries or other sources of current on the trackway to put the track device into the inactive or non-stopping condition, it is further proposed to employ a tra ck element structure which is caused to a. sume its inactive condition by merely closing a circuit without requiring any electrical energy.

With the type of system generally outlined above, it will be evident that the track rails of crossings, switch points, water pans, and similar iron and magnetic bodies along the trackway, will tend to produce an effect upon the car equipment similar to that produced by the regular track elements of the system when in their active stopping condition. Such tendency to produce an unnecessary and false stopping control, conveniently termed rail interference, is of course, highly objec- Serial No. 150,132.

tionable in systems of this character; and While various schemes for overcoming this rail interference have been suggested, it is proposed in accordance with the present invention to select the location and disposition of the cooperating elements on the car and on the trackway in such a way as to practically eliminate such rail interference.

Various specific objects, purposes and characteristic features of this invention will appear as the description progresses reference being had to the accompanying drawings showing, solely by way of example, one form which the invention may assume. In the drawings V Figs. 1 and 2 are plan and end views, respectively, of a construction of the car-element and its mounting;

Fig. 3 is a side view of thecar truck showing thelocation of the car element;

Figs. 4, 5 and 6 are enlarged fragmentary -views showing respectively in top plan with parts broken away,,in end elevation, and in side elevation, with pole pieces removed, the construction of the car element;

I F ig. 7 illustrates an arrangement of the car apparatus and circuits.

In the permissive or semi-automatic type of train control system under consideration, it is contemplated that a stopping impulse or influence will be communicated from the trackway to the passing vehicleat each caution signal, with or without a similar stopping impulse ata stop signal; and adjacent to the entrance of each block, (not shown) are track elements, T, T which may be located a short distance in the rear of the entrance to a block, at such entrance, or. a distance in advance thereof, depending upon the type of control circuits for these elements. In this particular case the track elements are to be located a short distance in the rear of the entrance of their block and their controlling condition is governed by a line relay 5 that is controlled in turn by the track relays, (not shown), of the corresponding block and the next block in advance. For further illustration, reference should be had to the above identified parent case.

In the type of inductive train control system to be described, that is, the type of system in which a controlling influence is produced on the car by virtue of the magnetic properties of the track element, it will be evident that a similar effect will be produced by other magnetic bodies along the trackway, such as switch points and track rails at cross ings, water pans, switch stands, and the like. In the specific type of system to be disclosed,

the track element produces its effect by changing the reluctance of a partial magnetic circuit on the car and inducing in a secondary coil included in said circuit a voltage which, by opposing the normally applied voltage of a battery or other source of current, causes operation of a suitable electro-responsive device; and unless the foreign magnetic bodies along the trackway are capable, by reason of their magnetic qualities and air gap relation to the car element, of producing as great a change in the reluctance of the car-carried magnetic circuit, the train control apparatus will not be operated. Since a track element is purposely constructed of iron with good magnetic qualities, and is laminated to avoid the weakening effect of eddy currents, it will, of course, be superior in this respect to track rails or other like magnetic bodies ordinarily encountered along a railway track.

When the track elements, however, are located between track rails, their upper surfaces must necessarily be on a level with, or somewhat below, the tops of the track rails, in order to avoid being struck by low hanging parts of vehicles; and these limitations, more particularly if it be attempted to keep the space between the track rails clear for the flanges of snow plows, makes the working air gap between the regular track element and the car element greater than between a track rail and said car element, with the result that the track rail has an advantage, so to speak, over the track element with respect to the air gap, and may under unfavorable conditions cause a false or unnecessary operation of the train control apparatus.

lVhile various expedients may be employed to neutralize or minimize this rail interfer ence, in accordance with the present invention it is proposed to dispose the track elements "outside of the track rails, in order that they may have their pole pieces elevated some dis tance above the plane of the tops of the running track rails. With this disposition of track elements, the car element being of course located accordingly, the working plane of the car and track elements is considerably above the level of the track rails, so that the track rails and other magnetic bodies are at a disadvantage both as to air gap and to magneticqualit-ies, and under ordinary working conditions will not produce an influence that is objectionable. lVhile various specific ar rangements and relative dispositions of the track and car elements may be employed in practice, one typical organization which has been found adaptable to an established clearance diagram for the railroads in this country consists of mounting the car and track elements with their center lines 19 inches outside of one or the other of the running rails, and with their working plane or center of the air gap 2 inches above the level of the top of the running rails.

In connection with this problem of rail interference, it is noted here that the coils on the car element are preferably so located that the primary coil P is ahead or leading as the vehicle travels in the normal direction of traffic, with its pilot or regular front end leading. The reduction in rail interference occasioned by such disposition is attributed to the fact that as the primary coil passes over the track an first, it magnetizes that rack rail with one polarity, and the residual magnetism tends to oppose a rapid and strong change of flux as the secondary coil passes over this track rail, it being observed that the magnetism of the track rail must be reversed to cause this change in flux.

In. Figs. 1 to 6 a form of mounting for a pair of U-shaped car elements, and cooperating track elements has been illustrated. In this arrangement, the car elements L have their pole pieces facing outwardly, and the cooperating track elements T are supported along the track facing inwardly.

Each car element L comprises a U-shaped core 140 consisting of U-shaped laminations of transformer iron riveted together. A portion of the laminations of the outstanding legs is cut narrower, thus resulting in a back yoke of general rectangular cross section, and outstanding legs of cruciform cross section. Une of these legs is provided with a primary coil P and the other with a secondary coil S, which are designed to have the proper number of turns and other constants to adapt them for the particular car apparatus with which they are to be used.

Each of the coils is surrounded by a tubular member comprising a casting 141 of nonmagnetic material, such as aluminum, manganese steel or the. like, and of the shape shown. These castings are provided with longitudinal slots 1 12 to prevent the flow of eddy currents due to change of flux in the legs of the U-shaped core. Iron pole pieces 142 are screw fastened to the outer ends of the tubular members 141 so that when these members are drawn in place by bolts to the angle bars 144 and heavy stirrups 1 15, the pole pieces 143 will be in good magnetic contact with the legs.

Two such car elements L are fastened to opposite ends of the carrier bars 146 by bolts 14? passing through stirrups 1 15. These carrier bars 146 may be supported from the tender truck or pony truck of a locomotive in any suitable manner, either resiliently, or rigidly, but have been illustrated as riveted to shortsections of channel bars 148 suitably fastened to the side frames of a railway truck. The particular railway truck illustrated does not form a part of the present invention, and therefore will not be described in detail. The track elements are of U-shape and disposed to face each other on opposite sidesof the track, and are provided each with a coil. The track elements are mounted in large blocks 150 of wood supported on the ends of the railway ties, and have inclined ends and sloping sides so that they will not be apt to be struck squarely by dragging equipment or like objects likely to encounter them.

In connection with the type of car and track elements shown in Figs. 1 to 6, it should be notcdthat variations in wheel wear do not appreciably change the air gap between the car elements and the track elements, but results in merely moving these elements somewhat out of horizontal alignment. If two car elements on opposite sides of the car are employed, as shown, when the car sways or shifts sidewise, the air gap between the car element on one side of the car decreases as the air gap on the other side of the car increases, thereby maintaining substantially the same result in combined. air gap and effect upon the control relay.

It should be noted that the car elements of this embodiment are supported so that the pole faces are disposed vertically and at a considerable distance above the rails, so that the probability of receiving false controlling influcnces from the track rails is very remote, and rail interference due to switch stands, iron relay casings, and the like, is likewise not apt to occur, because these devices are far enough from the line of action of the car elements to not interfere.

In Fig. 7 has been illustrated a form of semi-automatic train control system in which.

so that their pole faces are disposed in a ver tical plane instead of a horizontal plane; and there are two hold-by switches HS and HS whereby it is necessary that two men, presumably the engineer and the fireman, must cooperate and press the respective hold-by switches in order to pass a caution signal without incurring an automatic brake application. The brake control equipment is identical with the electro-pneumatic brake control apparatus B illustrated in Fig. 2-of the parent case, only the elcctro-pneumatic valve E. P. V. having been shown for convenience.

The car elements L and L comprise U- shaped magnet cores 140 having pole pieces 1&3, and are supported on a car in such a manner that the pole faces of the car elements face outwardly, as illustrated in Figs. 1 to 6. The legs of these car elements are provided with a primary and a secondary coil P and S, P and S, respectively, as heretofore described and the primary coil P is preferably arranged on the leg of the car element which is leading under normal conditions, for reasons heretofore explained, that is, the primary coil P is on the leg nearer the front end of a locomotive or electrically propelled vehicle.

The track elements T and T illustrated are located along the track and mounted with respect to the rails, so that the car elements will pass between them allowing an air gap large enough for mechanical clearance. These track elements T and T are of the construction illustrated in Fig. 1 and are provided with coils 159, 159 connected in series, in such a manner that the electro-motive-forces induced in the several coils by the passage of a pair of car elements thereby will be cumulative. The circuit by which said coils are connected passes throu h the front contact of the line relay 5.

The filament 156 of the audion is continually heated by the battery 160. Under normal conditions or where the car is moving between control points, a potential is maintained on the grid 157 of the audion by a battery 161 in a circuit including the secondaries S and S of the .car elements which may be traced as follows :-beginning at the positive side of the battery161, wires 162 and 163, secondary coil S of car element L, wire 164, second ary coil S of car element L wires 165 and 166, normally closed contact 58 of hold-by switch HS wire .167, normally closed contact 5 3 of the other hold-by switch HS, wire 168, grid .157 of the audion, filament 156, back to the negative side of the battery 161. The voltage thus impressed upon the grid 157 of the audion by battery 161 reduces the .plate resistance (that is, the resistance between the filament and the plate), thereby allowing a current to flow in the plate circuit, which may be traced as follows :beginning at the positive terminal of the battery 169 wire 170, front'conta-ct 168 of repeater relay R, wires 171 and 172, winding of repeater relay, wire173, plate 158 to filament 156 of the audion, through battery 161, to the negative side of the battery 169.

The winding of the E. P. V. and the primary coils P and P of the car elements are energized by a circuit which may be traced as follows:beginning at the positive side of the battery 169, wire 170, front contact 163 of repeater relay R, wire 171, reset switch RS, wire 174, winding 11 of the E. P. V., wire Opemtz'onrFig. 7.Assume now that a car equipped with the apparatus illustrated in Fig. 7 is moving between control points, and that said apparatus is in its normal condition, as illustrated in this figure. Under these circumstances, the filament'156 is heated to incandescence, whereby the voltage of the battery 161;, which is impressed upon the grid 157 of the audion through the circuit heretofore traced, will cause a: plate current to be setup in the plate circuit suificient in amount to maintain the repeater relay R energized, and maintain its front contact 163 closed. The energization of the repeater relay completes the circuit through the train control device E. P. V. and the primary coils P and P of the car elements, thus preventing an automatic brake application.

Assume that the car under these conditions is approaching a caution signal and that the associated track elements T and T are in their open circuit or danger condition, and that the engineer and fireman have agreed to operate the hold-by switches HS and HS As the engineer and fireman press their respective hold-by switches, an auxiliary grid circuit, shunting out the coils S and S will be closed, said circuit being traced as follows :l;ie, inning at the positive side of the battery 161, wires 162 and 178, contact 17 of hold-by switch HS, wire 179, contact 47 of hold-by switch l-lS wires 180 and 166, normally closed contact 53 of hold-by switch H.55 wire 16?, normally closed contact 53 of hold-by switch HS, wire 168, grid 157 to the filament 156 of the audion, back to the negative side of the battery 161.

This circuit, just traced, (due to shunting coils S and S around the grid 157,) causes the impulse of one cycle of E. M. 11, generated in the secondary coils S and S (due to the secondary coils passing by their associated track elements, when in active condition, that is unchoked, in inductive relation thereto,) to be dis pa ed in the following closed circuit :-l. eginning at the secondary coil S, wire 16 i, secondary coil S wires 165 and 180, Contact 1-7 of hold-by switch HS, wire 179, contac 17 of hold-by switch HS, wires 1"?8 and 163, back to the secondary coil S. The flow of current in the circuit just traced will. of course, in no way affect the audion or devices controlled thereby, and as soon as the caution signal has been passed, the

engineer and fireman may release their holdby switches, thus putting the car apparatus back into its normal condition.

If either the engineer or fireman attempts to defeat the invention by fastening down the hold-by switches HS or HS, after a longer period than that allowed by the timing devices comprising the spring a9 and dash pot and similar devices 19 and 50 one or both of the normally closed contacts and 53 of the hold-by switches will be opened,

thus breaking the circuit to the grid of the audion which will decrease or practically interrupt the fiow of current in the plate cirsuit thereof, thus deenergizing the repeater relay R which will interrupt the circuit through its-front contact 163 and through the-train control device E. P. V., thereby stopping the train. Thus, the engine men can not defeat the purpose of the train control system by tying these hold-by devices down permanently.

7 Assume now that a car with its train control apparatus in its normal condition is approaching a caution signal with the associated track elements in their open circuit or danger condition, and that neither the engineer nor the fireman, or but one of these, sees the signal and does nothing to prevent an automatic application of the brakes. Under these conditions as the car elements pass by the track elements, a single cycle of E. M. F. will be generated in the two secondary coils S and S which are connected in series so that their voltages are cumulative. The grid circuit of the audion has the secondary coils S and S connected in such a manner with respect to the battery 161 that the first wave of the cycle of E. M. F. generated is in opposition to the voltage of the battery, thus causing a reduction of potential on the grid G of the audion to a sutficient extent to reduce the plate currentbelow the dropaway value of the repeater relay R, thereby causing the repeater relay to interrupt the circuit through the train c011- trol device E. P. V. This operates to impose the desired control. The second wave of the cycle of E. M. F. will have no etlect, because the repeater relay R is of the stick type, and after its contact has once been opened, it will remain deenergized until restored by some other means.

For the purpose of restoring the repeater relay 1%, as well as the train control device E. P. V. to its normal condition, the reset switch RS must be operated. If this reset switch BS is operated, the following circuit will be completed :beginning at the positive side of the battery 169, wires 170 and 182, reset switch RS closed, wire 172, winding of repeater relay R, wire 173, plate 158 to the filament 156 or" the audion, through battery 161, back to the negative side of the battery 169. The completion 01 this circuit will energize the repeater relay R, which when energized will complete the normal holding circuit by its front contact 163 shunting the reset switch. This reset switch is protected against misuse by making it. accessible only from the ground, or by protecting it in any other manner as heretotore explained. If it is only accessible trom the ground, the train must be brought to a stop in order to reset the train control apparatus. Secondly, the reset switch RS has been protected so that it can not be pe'rma'nently fastened down before starting on a trip, in that, the circuitthrough the train control device is completed through a back cont-act on the resetvswitch, and if fastened down, the winding of the train control device E. P. V. is'permanently deenergized', thereby continuously maintaining an automatic brake application.

The above rather specific description of one form of the present invention has been given solely by Way of illustration and is not intended in any manner whatsoever in a limiting sense. Obviously the invention can assume many different physical forms and is susceptible of numerous modifications, and all such forms and modifications are intended to beincluded by this invention as come within the scope of the appended claims.

Having described my invention, I now claim I g 1. In a train control system wherein control influences are transmitted, by the magnetic properties. of iron bodies along the trackway, on suitable car-carried devices, carcarried influence receiving means located a distance above the track so as not to receive a control influence from the running and intersecting track rails, cooperating traflic controlled track devices so located with respect to the running rails that a control influence will be transmitted through said receiving means when said track devices are in their influence transmitting condition, a thermionic detector controlled by said influence receiving means, and protected means for preventing control of said detector by said receiving means. y

2. In a train control system wherein control influences are transmitted, by the magnetic properties of iron bodies along the trackway, on suitable car-carried devices, car-carried influence receiving means located a distance above the track so as not to receive a control influence from the running and intersecting track rails, cooperating traffic controlled track devices so located with respect to the running rails that a control influence will be transmitted through said receiving means when saidtrack devices are in their influence transmitting condition a thermionic detector controlled by said influence receiving means, and means for preventing the control of said thermionic detector by said receiving means, said last mentioned means being protected against holding it permanently in its operative position.

3. In a train control system, a car-carried influence receiving means, a track element associated therewith, a detector controlled by the receiving means, and acknowledging means for shunting the receiving means around the detector to permit dissipation of energy from the receiving means without atfecting the detector.

4. In a train control system, a car-carried influence receiving means, a trackelement as sociated therewith, a detector controlled by the receiving means, and acknowledging means" for shunting the receiving means around the detector to permit dissipation of energy from the receiving means without atfecting the detector, the acknowledging means including a plurality of manually op erable'devices spaced from each other to prevent simultaneous operation by a single operator. I v 5. In a train control system, a trackway in ductor, a train carried receiver, a train control device, a detector controlled by the receiver and controlling operation of the train control device, and a plurality of separate, spaced, manually operable, acknowledging means for preventing the receiver from atfecting the detector to cause a train control.

6. In a train control system, a trackway inductor, a train carried receiver,a train control device, a detector controlled by the receiver and controlling operationot the train control device, a plurality of separate, spaced, manually operable, acknowledging means for preventing the receiver from affecting the detector to cause a train control, and a time element for each acknowledging means automatically preventing its inhibiting eflectbeyond a predetermined time interval.

7. In a train control system, a track inductor, atrain carried receiver, a train control device, a detector controlled by the receiver and controlling operation of the train-control device, a plurality of separate, spaced, manually operable, acknowledging means for preventing the receiver from affecting the detector to cause a train control, a normally energized circuit for the detector inclu-ding the receiver, an acknowledging switch manually operable to shunt the receiver out of said normally energized circuit for the detector, and a time element associated with the switch for automatically breaking the thus resulting detector energizing circuit after a predetermined time interval whereby to cause operation of the train control device.

8. In a train control system, an inductor, a receiver, a thermionic detector controlled by the receiver, a train controljdevi'ce controlled by the detector, and a plurality of separate acknowledging means, incapable of simultaneous operation by a single operator, for ointly preventing energy impulses from the receiver from affecting the detector.

9. In a train control system, a car-carried receiver, a thermionic detector with its grid circuit including the receiver and a source of energy, a brake control device controlled by the detector plate circuit, and means to shunt the receiver out of said grid circuit.

10. In a train control system, a car-carried receiver, a thermionic detector with its grid single operator, for shunting the receiver out.

of the grid circuit.

12. In a train control system, a car-carried receiver, a thermionic detector with its grid circuit including the receiver and a source of energy, a train control device controlled by the detector plate circuit, separate manually operable acknowledging switches in series in the grid circuit, and positioned to be incapable of simultaneous operation by a single operation, for shunting the receiver out of the grid circuit, and time controlled means associated with the switches for automatically breaking the grid circuit after the lapse of a predetermined interval of time from the operation of the switches.

13. In a train control system, faced inductors of like form, one at each side of a track, positioned with their faces in opposition each to the other, two faced car-carried receivers each of the same form as the inductors and positioned each to pass its face adjacent to, and out of contact with, each inductor face, and train control means controlled by the receivers.

14. In a train control system, inductors, one at each side of a track, arranged opposite to each other, two car-carried receivers positioned to respectively pass adjacent to, and out of contact with, the inductors, and train control means controlled by the receivers, the inductors and receivers having coacting pole fa ces lying in substantially vertical planes.

15. In a train control system, inductors, one at each side of a trackway, placed one opposite the other, inwardly facing vertical pole faces on the inductors, and car-carried receivers positioned to respectively pass adjacent the inductors, and having cooperating, vertical, outwardly directed pole faces.

16. In an automatic train control system, the combination with a normally energized electrically operable brake control mechanism of the type which ifmomentarily de-energized will remain de-energized until restored by some other means, means governed from the trackway for de-energizing said brake control device, two manually operable devices one of which is accessible to the engineer and the other of which is accessible to the fireman but is not accessible to the engineer while operating said one manually operable device which if both operated substantially simultaneously at the proper time will prevent de-energization of said brake control device, separate means associated with each of said two manually operable devices for causing de-energization of said brake control device if such manually operable device is left in its active condition too long, and means for restoring said brake control mechanism to normal accessible only from the ground for operation thereof.

17. In an automatic train control system, in combination, a normally energized electrically operable brake control mechanism of the type which if momentarily de-energized will remain de-energized until restored by some other means, means governed from the trackway for causing de-energization of said brake control device, two manually operable devices one of which is accessible to the engi neer and theother of which is accessible to the fireman but is not accessible to the engineer while operating said one manually operable device, which, if both be operated substantially simultaneously at the proper time, will prevent de-energization of said brake control device, separate means associated with each of said manually operable devices for causing de-energization of said brake control device if such manually operable device he not returned to its inactive condition very shortly after said proper time, and manually operable means, accessible only from the ground, for restoring said brake control mechanism to normal.

In testimony whereof I afiix my signature.

CHARLES S. BUSHNELL. 

